Four policemen were killed and four others injured in a drive-by shooting in the city of Mosul on Wednesday, a local security source said.

"The incident occurred when unknown gunmen in a car opened fire around midday on a police patrol in the Rashi Kor neighborhood in central the city, killing four policemen and injuring four others," the source told Xinhua on condition of anonymity.

Mosul, some 400 km north of Baghdad, is the capital of the Nineveh province which has recently been a focus of a major offensive against the al-Qaida and other militant groups.

On Jan. 25, Nuri al-Maliki, the Iraqi Prime Minister has promised a "decisive battle" in the Nineveh province to uproot the al-Qaida militants from their last stronghold in the province where they were believed to be regrouped after being defeated in Baghdad and other Iraqi provinces.